"LLM would have to spend a lot of time reasoning about lifetimes"

Let's set aside the fact that Go is a garbage collected language while Rust is not for now...

Do you prefer to let LLM reason about lifetimes, or debugging subtle errors yourself at runtime, like what happens with C++?

People who are familiar with the C++ safety discussion understand that lifetimes are like types -- they are part of the code and are just as important as the real logic. You cannot be ambiguous about lifetimes yet be crystal clear about the program's intended behavior.

For many (most) types of objects lifetimes can be a runtime property just fine. For e.g. a list, in rust/c/c++ you would have to do an explicit decision how long should it be "alive", meanwhile a managed language's assumption that when it's reachable that is its lifetime is completely correct and it has the benefit of fluidly adapting to future code changes, lessening maintenance costs.

Of course there are types where this is not true (file handlers, connections, etc), and managed languages usually don't have as good features to deal with these as CPP/Rust (raii).

Fair point, and it depends on whether you're building code to last a decade, or creating a quick proof of concept.